Regex replace using a substring of the regex result value

Question

I've been reading a ton of material and thought I had found my solution but no luck. I need to find apostrophes contained in a name and then replace them with a double. I am loading a file to an array and then looping through that, looking for the apostrophes. The catch is that each row can have several apostrophes so that's why it's not a simple find and replace.

Here is a sample of the file:

   create(xxxxxxx)using(xxxxxxx)name('O'Doe, John')
   replace(xxxxxxx)instdata('ab 1234 ')
   create(xxxxxxx)using(xxxxxxx)name('Doe, O'Jane')
   replace(xxxxxxx)instdata('ab 5678 ')

There are other lines inbetween but they don't contain apostrophes.

Here is what I have so far:

    $Pattern = "[A-Z]'[A-Z]"
    $user = gc C:\Temp\mfnewuser.ins
    for ($i = 0; $i -lt $user.count; $i++) {
       if ($user[$i] -match $Pattern) {
       $user[$i] = [regex]::replace($strText, $Pattern.substring(2,1), "''")
       $user | out-file C:\Temp\mfnewuser.ins
       }
    }

I'm looking for a capital letter, followed by an apostrophe, followed by another capital. Because of the other commas, I can't just do a global replace. I know my pattern matching is working but I can't seem to manipulate it with the substring. The substring looks at $Pattern as a string instead of the result of a regex. If I can save the regex result to a variable, that would be great. I think then the replace would be easy.

Tried this as well but no luck either:

    $Pattern = "[A-Z]'[A-Z]"
    $NewPattern = "[A-Z]''[A-Z]"
    $f = Get-Content C:\Temp\mfnewuser.ins
    $f = $f -replace $Pattern, $NewPattern
    $f | out-file C:\Temp\mfnewuser.ins

I may be approaching this all wrong and there is an easier way but I haven't seen anything yet.

EDIT: Based on Bill_Stewarts example below, I've got this to work on the First Name but not yet the Last Name:

$Pattern = "[A-Z]'[A-Z]"
$user = gc C:\Temp\mfnewuser.ins
for ($i = 0; $i -lt $user.count; $i++) {
    if ($user[$i] -match $Pattern) {
        $user[$i] = $user[$i] -replace "(.*[A-Z])'([A-Z]+.*)", "`$1''`$2"
        $user | out-file C:\Temp\mfnewuser.ins
        }
    }

The regex is taylored to what forms you expect to see surrounding the apostrophe. Try one of @hwnd's regex's. — user557597
– user557597, Commented Oct 4, 2013 at 19:15
Looks like we got the same thing - ([A-Z])'([A-Z]) should be sufficient. — Bill_Stewart
– Bill_Stewart, Commented Oct 4, 2013 at 19:17

Bill_Stewart · Accepted Answer · 2013-10-04 19:10:59Z

1

Perhaps something like this?

get-content "test.txt" | foreach-object {
  $_ -replace "([A-Z])'([A-Z])", "`$1''`$2"
}

Regular expressions can be grouped using ( ) and the -replace operator supports substring replacement ($1 and $2).

edited Oct 4, 2013 at 19:10

answered Oct 4, 2013 at 18:23

Bill_Stewart

24.9k5 gold badges55 silver badges70 bronze badges

Sign up to request clarification or add additional context in comments.

8 Comments

N1tr0 Over a year ago

Thanks, I'll give this a shot. I've seen the $1 and $2 references before but wasn't sure what those were for. How do those work?

Bill_Stewart Over a year ago

$0 means 'entire string that matched', $1 means 'first grouped subexpression', $2 means 'second grouped subexpression', and so forth.

user557597 Over a year ago

Wouldn't ([A-Z])'([A-Z]) be sufficient?

Bill_Stewart Over a year ago

That's enough for a match, but you need enough to do the replace.

N1tr0 Over a year ago

OK, it kind of working. It doubles-up the single-quote on the first name but not on the last: ('O'Last, O''First'). I'm still new to regex and don't yet understand all of the symbols used.

|

hwnd · Accepted Answer · 2013-10-04 19:30:53Z

1

Replace your line, with the following.

$user[$i] = $user[$i] -replace "([A-Z])'([A-Z])", "`$1`''`$2"

Or try one of the following. This should suffice.

get-content "mfnewuser.ins" | foreach-object {
  $_ -replace "([A-Z])'([A-Z])", "`$1`''`$2"
} | set-content "mfnewuser.ins"

...

get-content "mfnewuser.ins" | foreach-object {
  $_ -replace "([a-zA-Z', ]+)'([a-zA-Z', ]+)", "`$1`''`$2"
} | set-content "mfnewuser.ins"

edited Oct 4, 2013 at 19:30

answered Oct 4, 2013 at 18:50

hwnd

70.9k4 gold badges100 silver badges135 bronze badges

Collectives™ on Stack Overflow

Regex replace using a substring of the regex result value

2 Answers 2

8 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

8 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related